What injective means?

Could you please clarify for me what the term "injective" actually means? I've encountered it in the context of cryptography and blockchain technology, but I'm having a hard time grasping its precise definition. Is it related to functions in mathematics? If so, how does it apply to the realm of cryptocurrency and finance? Could you provide an example or two to illustrate its usage in this field? It would be greatly appreciated if you could explain this concept in layman's terms, as I'm still getting familiar with the intricacies of this domain. Thank you in advance for your assistance.